Tibia Fractures
The tibia, the larger of the two lower leg bones, can be broken in three areas: the tibial plateau, near the knee; the shaft; and tibial plafond, near the ankle. Fractures in each region have their own distinct concerns. Tibial plateau fractures are peri-articular (joint-adjacent) fractures, and thus may lead to post-traumatic arthritis. Shaft fractures are associated with acute compartment syndrome and, owing to their subcutaneous location, have greater difficulty healing. They are also associated with compartment syndrome. Tibial plafond fractures [covered in the ankle fracture chapter] are also peri-articular injuries, and they too can be complicated by post-traumatic arthritis.
Most tibial fractures are best managed with surgical fixation. Stabilizing the tibia non-operatively requires a long-leg cast, one that crosses the knee and ankle joints; surgical treatment thereby liberates the knee and ankle. Permitting motion of those joints helps avoid the stiffness that cast immobilization might otherwise induce.
The much smaller lower leg bone, the fibula, is usually fractured when the tibia is broken. The injury pattern is commonly called a “tib-fib” fracture. Unlike the case of a “both bones” fracture of the forearm, where both the radius and ulna must be treated to restore rotation function, specific treatment of the fibular shaft is usually not required. That is because the fibula supports only approximately 10% of the bodyweight and the tibial shaft can adapt to greater loads if needed. Fibular fractures are problematic usually only to the extent they involve the knee or ankle joints, or a fracture fragment injures the nearby common peroneal nerve.
Structure and Function
The tibia and fibula are the two bones of the lower leg. The tibia is larger and located more medially and anteriorly; the fibula is smaller, lateral, and posterior (Figure 1).
Proximally, the tibia articulates with the femur at the knee joint, which allows for flexion and extension of the lower leg. Distally, the tibia and fibula articulate with the talus at the ankle joint, which allows for dorsiflexion and plantarflexion of the ankle.
The medial tibial plateau is concave and bears 60% of the joint load across the knee. The lateral plateau is convex. Its elevated position, as well as its relative weakness make it more prone to fracture.
The popliteal fossa behind the knee holds the popliteal artery and vein. The fossa is also home to the tibial and common peroneal nerves, which innervate the lower leg. The common peroneal nerve lies close to the proximal fibula, where it divides into superficial and deep branches. The common peroneal nerve is at risk for injury with proximal fibula fracture (see Figure 2). The extrinsic muscles of the foot originate in the lower leg. These muscles are contained within four fascial compartments: the anterior, lateral, deep posterior, and superficial posterior compartments (Figure 3). The anterior compartment contains the tibialis anterior, extensor digitorum longus (EDL), and extensor hallucis longus (EHL) muscles, which act to dorsiflex the foot and extend the toes. These muscles are innervated by the deep peroneal nerve, which runs within the compartment, as well.
The deep peroneal nerve provides sensation to the first web space on the dorsum of the foot, between the great and second toes. Loss of normal sensation in the first web space may be one of the earliest signs of compartment syndrome.
The lateral compartment contains the peroneus longus and brevis muscles, which evert the foot. These muscles are innervated by the superficial peroneal nerve, which also provides sensation to most of the dorsum of the foot (except the first web space).
The deep posterior compartment contains the flexor hallucis longus (FHL), flexor digitorum longus (FDL), and tibialis posterior muscles, which act to plantarflex the ankle, flex the toes, and invert the foot. The deep posterior compartment muscles are innervated by the tibial nerve.
The superficial posterior compartment muscles are also innervated by the tibial nerve. These muscles, the plantaris, soleus, and gastrocnemius muscles, plantarflex the ankle. The gastrocnemius also assists with knee flexion, as it originates from the posterior femur and crosses both the knee and the ankle joints. The terminal branches of the tibial nerve provide sensation to the posterior distal leg and sole of the foot.
The knee is stabilized by four primary ligaments: the medial collateral ligament (MCL), lateral collateral ligament (LCL), anterior cruciate ligament (ACL), and posterior cruciate ligament (PCL).
Due to its close proximity to the knee and tethering to its posterior soft tissues, the popliteal artery is at risk when there is extensive knee trauma. The artery is particularly high risk when the knee is injured while in extension, when the artery is under tension and closest to the bone. (Figure 4).
Figure 2: The course of the common peroneal nerve is shown at left. The nerve lies posterior, behind the tibial plateau and fibular head, until it wraps around the fibular neck on its course to the anterior aspect of the leg. A fracture of the proximal fibula, as shown in the x-ray to the right, places the nerve at risk. (X-ray courtesy of Pathoanatomy and Injury Mechanism of Typical Maisonneuve Fracture https://doi.org/10.1111/os.12733)
Figure 3: The four compartments of the leg and their contents are shown in a cross section (modified from Wikipedia). The anterior compartment is shown in red, lateral in blue, deep posterior in green and superficial posterior in purple.
Figure 4: Angiography (left) demonstrates the proximity of the popliteal artery to the bones of the knee. As see in the annotated image (right) the popliteal artery (appropriately in red) is just posterior to the knee joint. (Modified from Cooper N, Roshdy M, Sciarretta JD, Kaufmann C, Duncan S, Davis J, Macedo FI. Multidisciplinary team approach in the management of popliteal artery injury. J Multidiscip Healthc. 2018;11:399-403)
Patient Presentation
Patients with tibia fractures typically present with a history of an acute injury. They have pain, swelling, deformity, and inability to bear weight.
Tibial shaft fractures are the result of a direct force or a torsional injury and usually present with obvious deformity.
Tibial plateau fractures are usually the result of falls, motor vehicle accidents, and sports injuries. The mechanism of injury is usually an axial load in combination with a varus or valgus force, depending on the position of the knee at the time of injury.
Tibial plateau fractures may also be caused by relatively low energy twisting mechanisms, particularly if the patient is obese or elderly. A knee effusion (hemarthrosis) is present on exam. It is important to assess for evidence of other injuries including knee dislocation, which may have spontaneously reduced itself prior to presentation.
A careful skin check should be part of every exam, as the tibia is the most common location of open long bone fractures.
Due to the risk of neurovascular injury, it is imperative to perform a careful motor and sensory exam. The sensory examination of the deep and superficial peroneal nerves is most informative, as motor function will be inhibited by pain, and its absence is therefore nonspecific. An initial vascular exam assessing the dorsalis pedis (DP) and posterior tibialis (PT) artery pulses is critical as well.
Swelling is common after tibial fracture and predisposes to compartment syndrome. Compartment syndrome (see https://orthopaedia.com/page/Acute-Compartment-Syndrome) may be present in 10% or more of tibial shaft fractures.
Objective Evidence
Patients with suspected tibia fractures should have x-rays performed of the knee, tibia and fibula, and ankle (see Figure 5a. An anterior-posterior (AP), lateral, and oblique views of the knee are needed for suspected tibial plateau fractures (Figure 5b).
Tibial plateau fractures are characterized by location: the lateral tibial plateau; medial tibial plateau fracture; or both. AP and lateral radiographs of the leg (tibia/fibula) can characterize tibial shaft fractures. Tibial shaft fractures are best described by their location in the bone (e.g., “mid-shaft”); the orientation of the fracture line (e.g., “transverse”); the presence of comminution, displacement and angulation; and the status of the soft tissue (e.g., open vs closed).
For peri-articular fractures, that is, injuries near the knee and ankle, a CT scan is useful for assessing the fracture pattern and for preoperative planning. That’s because even small amounts of displacement can interfere with optimal function. If there are concerns of associated ligament injuries, an MRI may also be indicated.
With any suspicion of a vascular injury, the Ankle Brachial Index (ABI) should be measured. The ABI is the ratio of the systolic blood pressure at the level of the dorsalis pedis (DP) or posterior tibial (PT) arteries (ankle) divided by the systolic pressure at the level of the brachial artery. An ABI below 0.9 is concerning for a vascular injury. If there is any doubt about the adequacy of flow, a vascular consult should be obtained urgently. In such cases, the consultant usually will order an angiogram.
If survival of the limb is imminently threatened, the best decision may be to proceed directly to the operating theatre where an “on table angiogram” can be performed in conjunction with an emergency surgical procedure.
X-rays should be evaluated closely for evidence of a knee dislocation, as dislocation is frequently (15%) associated with neurovascular injury.
Epidemiology
Tibia fractures are common. Tibia fractures occur in all age groups, but incidence tends to follow a bimodal age distribution, with high energy fractures in younger patients and low energy fractures in older patients.
Differential Diagnosis
The diagnosis of a traumatic tibial fracture is fairly straight forward, but it is important to accurately assess the fracture patterns and the extent of associated soft tissue damage. There may be neurovascular deficits, compartment syndrome, and ligament injuries – none of which are necessarily seen on plain radiographs.
Radiographs may also reveal an underlying pathological process such as a bone tumour or osteoporosis.
Red Flags
The “red flags” of tibia fractures are any sign or symptom that would suggest a vascular injury or compartment syndrome.
Particular attention must be paid to high energy fractures. These fractures may be associated with a knee dislocation and vascular injury. Consumption of increasing amounts of narcotic pain medicines after reduction of a tibia fracture is worrisome for compartment syndrome.
Blood on the skin without any grossly obvious wound may suggest a subtle open fracture – a so-called “inside out” open fracture. The term refers to the mechanism of injury: the break in the skin is caused by a spike of the fractured bone. This penetrates the skin from within, but then recoils back below the skin. This mechanism leaves just a small puncture wound, which may be overlooked except for the bleeding it causes.
Treatment Options and Outcomes
On presentation in ER
If there is marked deformity, gentle traction and application of a splint under sedation can markedly improve limb alignment, provide temporary stability, improve pain control. Aligning the bone also reduces the risk of progressive neurovascular injury from soft tissue tethering. Any skin breaches should be noted, cleansed and dressed prior to application of the splint.
Open fracture sites should be cleaned and irrigated with sterile normal saline (in preference to soap or antiseptics) and covered with a saline-soaked sterile dressing as a prelude to further exploration and debridement in OR.
The most important intervention shown to reduce risk of infection after open fracture is the early administration of appropriate IV antibiotics. The choice of antibiotics will depend on the context, but high energy, grossly contaminated or farmyard injuries require the broad coverage against gram negative and positive bacteria, as well as anaerobic organisms. Tetanus prophylaxis should be given as well, if indicated.
Non-operative Management
Closed tibia shaft fractures can be treated with immobilization if the alignment is acceptable and the fracture is sufficiently stable. A splint is used first, to accommodate the inevitable swelling. The splint is converted to a long-leg cast once the swelling subsides. Notably, the stabilization of a long bone initially requires a cast that crosses the joints above and below the fracture. In the case of a tibia fracture, the knee and ankle must be immobilized initially. To minimize joint stiffness, casts should be converted to a functional brace or short-leg cast once some bone healing is seen.
When cast immobilization is used as fracture treatment, fragments can move and a malunion can develop. Patients must be followed closely to monitor for shortening, angulation, or rotation of the fracture.
Minimally displaced tibial plateau fractures caused by low energy mechanisms of injury, especially in patients who are non-ambulatory or close to it, can be treated in a knee immobilizer. It must be assumed that most older patients cannot reliably restrict weight bearing, so this approach must be reserved for fractures that will not displace when the patient inevitably stands on the affected leg.
Non-operative management may also be the preferred treatment option, even with displaced fractures, when the patient is too sick to undergo surgery. Joint replacement, after the fracture has healed, may be an option if the patient’s medical condition improves and post-traumatic arthritis develops.
Surgical Management
Surgical management is required for open fractures, vascular injury, and compartment syndrome. Even without those considerations present, most tibial fractures are best managed with internal fixation with plates, intramedullary nails, or a combination of the two techniques. Surgical fixation maximizes anatomic restoration and allows the knee and ankle to move.
External fixation is typically used as a temporizing measure. Depending on the location of the fracture, the external fixator many need to span the ankle or knee (Figure 6). An external fixator can be applied quickly and will help realign the fracture and provide bony stability in even the most medically unstable patients.
The location of external fixation pins can be chosen judiciously, such that vascular injuries and severe soft tissue defects can be treated while the bone is held in place. Pin tract complications, such as loosening and infection, are common. External fixation can be converted to definitive internal fixation devices once all vascular and soft tissue injuries have been addressed, and there is no evidence of infection.
If there is a compartment syndrome, fasciotomies must be performed prior to fixation.
Open reduction and internal fixation (“ORIF”, pronounced oh-are-eye-eff) is the definitive treatment of choice for tibial plateau fractures. The aim of ORIF (Figure 7) is anatomic reduction of the articular surface and rigid stabilization. Rigid fixation allows early joint range of motion of the knee joint. Patients are often placed in a hinged knee brace to maintain normal alignment and allow the ligaments, if injured, to heal.
Intramedullary nailing is usually the treatment of choice for tibial shaft fractures (Figure 8). To place the nail, an incision is made at the knee, the bone fragments are aligned, and a nail is placed in the medullary canal of the tibia. The nail can be locked with screws proximally and distally. The main goal of nailing is to restore the length, alignment, and rotation of the tibial shaft. Patients are typically able to bear full weight as tolerated after surgery. Some patients report knee pain near the entry site of the nail.
In cases with significant soft tissue damage –a crush injury with transection of the neurovascular bundle, say– amputation at the time of presentation may be the best option. If a prompt amputation is performed, a prosthesis can be fitted, and rehabilitation commenced almost immediately. The unhappy alternative to early amputation in some patients with devastating injuries is a protracted course of multiple failed operations, chronic pain and drug dependency, financial hardship due to loss of work and hospital bills, psychological depression – and an amputation is a salvage procedure at the end of this sorry course. Needless to say, no patients want to lose a limb, but if an injury is going to lead to loss of the leg regardless, or lead to a limb that is viable but unbearably painful and functionally inferior to a prosthesis, it is better to perform the amputation expeditiously. (There are many examples of very high functioning athletes with prosthetic limbs.)
Figure 6: Bilateral external fixators are used here to temporarily stabilize bilaterally open tibia fractures. (courtesy of Jaimo Ahn, MD, PhD, FACS, FAAOS, Harold W. and Helen L. Gehring Research Professor of Orthopaedic Surgery, University of Michigan)
Figure 7: ORIF of a tibial plateau fracture with a plate and screws. (courtesy of Jaimo Ahn)
Figure 8: A locked intramedullary nail holds a tibia fracture in anatomic alignment. Note that the fibula is not fixed, but rather is stabilized indirectly by the tibia. (image courtesy of Dr. Jaimo Ahn)
Risk Factors and Prevention
There is not much that can be done to prevent tibia fractures. Fractures are often the result of falls from height, sports injuries, and motor vehicle crashes – and people like playing sports and driving cars. Optimizing bone health may prevent some lower energy fractures in the elderly population.
References
Part or all of this article or section is derived from TibiaFractures by Orthopaedia.com, used under CC-BY-NC-SA
